A goal in the mass-production of blow-molded plastic containers is to provide a container structure which provides the desired functionality yet which utilizes a minimum of plastic. The container structure must be sturdy enough to withstand filling, shipping, and use. In addition, the container structure must maintain an aesthetic appearance from initial manufacture through sale and use of the container. Such plastic containers have the advantage of being completely recyclable.
Many liquid household products sold commercially are contained in blow-molded plastic containers. An example of such a product is liquid laundry detergent. Some of these detergents are sold in plastic containers having pour spouts, caps that provide measuring cups, means for providing drain back of the unused liquid from the measuring cap, and other features which provide pouring of controlled quantities of liquid from the container.
Many known blow-molded plastic container structures used in the sale of liquid household products require the use of separate injection molded parts to provide a pour spout and/or a cap having a drain back feature. For instance, U.S. Pat. No. 4,981,239 issued to Patel et al. discloses a blow-molded container having a separate injection molded cylindrical fluid retaining means to provide a drain back feature and to allow the closure to be attached to the container. Many other patents such as U.S. Pat. Nos. 2,743,844; 2,763,403; 2,848,142; 3,318,496; 3,369,710; 3,434,637; 4,128,189; 4,550,862; 4,706,829; 4,773,560; 4,830,234; and 5,188,249 each disclose a container having a separate pour spout fitted into the mouth of the container over which a separate closure is fastened.
Manufacture of these multiple part container structures utilizing known blow-molding and injection molding techniques requires the use of substantial amounts of plastic and increases the steps and complexity of producing a finished container by requiring the separate parts to be molded with precision so they can be mated. The additional plastic and required manufacturing steps increases the overall cost of manufacturing the container which is ultimately borne by the consumer.
Several expired patents disclose the use of a pour spout in the finish of a bottle without requiring the use of additional mated parts. For example, U.S. Pat. No. 1,814,659 issued to Barrol, U.S. Pat. No. 2,035,877 issued to Geerlings and U.S. Pat. No. 2,059,910 issued to Ravenscroft all disclose bottle finishes having a pouring spout formed therein. All these patents were issued before the advent of blow-molded plastic containers.
The assignee of the present application has manufactured hand-held blow-molded plastic containers having a pinched area adjacent the finish of the container for providing a venting function during pouring. See U.S. Pat. No. 4,838,464 issued to Briggs. During pouring of contents from the Briggs container, air flows through the vent passage to equalize air pressure in the container so that liquid can flow from the container in a continuous stream. The Briggs container is particularly suited for containing motor oil.
Although various ones of the referenced containers may function satisfactorily for its intended purpose, there is a need for a blow-molded plastic container having a unitary construction which provides a built-in pour spout affording controlled pouring of desired quantities of contained liquids. Such a container should also be capable of being manufactured readily utilizing conventional blow-molding equipment while requiring a minimum amount of plastic to reduce the cost of manufacture.